1. Field of the Invention
The present invention relates to a starter system for cranking an internal combustion engine.
2. Description of Related Art
An inertia-engagement-type starter motor having a pinion that engages with a ring gear of an internal combustion engine by its own inertia has been widely used. A rotational torque of an electric motor is transmitted to the pinion engaging with the ring gear thereby to crank up the engine. After the engine is cranked up, the pinion is disengaged from the ring gear and returned to its original position.
Another type of starter motor, a so-called rotation-restricted-engagement-type starter motor is also known. An example of this type of starter motor is disclosed in JP-U-57-36763. A pinion of this type of starter motor is coupled to an output shaft of an electric motor via a helical spline formed on the output shaft. Rotation of the pinion is restricted to push forward the pinion thereby to establish its engagement with the ring gear of the engine.
There has been a problem, however, both in the inertia-engagement-type starter and in the rotation-restricted-engagement-type starter. In the inertia-engagement-type starter, when a driver inadvertently restarts the starter, the pinion abuts the ring gear rotating at a high speed without being able to engage with the ring gear. Therefore, a high impact noise is generated at the abutment, and the pinion or the ring gear may be damaged.
The problem is more serious in the rotation-restricted-engagement-type starter. When the starter is inadvertently restarted while the engine is running, the pinion which is unable to engage with the ring gear is forcibly rotated while its rotation is restricted by a restricting member. Therefore, it is highly possible that the restricting member and its associated components are damaged by the forcible rotation of the pinion. To avoid this problem, it may be necessary to provide the restricting member with a higher strength, which makes the size of the restricting member larger.
The present invention has been made in view of the above-mentioned problem, and an object of the present invention is to provide an improved starter system in which the inadvertent restart of the starter is automatically prevented.
The starter system for cranking an internal combustion engine includes a starter having an electric motor, and a starter circuit for supplying electric current to the starter. A key switch that is closed by turning on an ignition switch is connected in the starter circuit, and current is supplied to the starter by closing the key switch.
A pinion of the starter is engaged with a ring gear of the engine by inertia of the pinion in an inertia-engagement-type starter. In a rotation-restricted-engagement-type starter, rotation of the pinion which is coupled to an output shaft of the starter via a helical spline is restricted by a rotation-restricting member. The rotation-restricted pinion is pushed forward to engage with the ring gear.
In the case where the inertia-engagement-type starter is used in the system, the pinion cannot engage with the ring gear when a driver inadvertently restarts the starter while the engine is running. High impact noises are generated by abutment of the pinion against the ring gear, and the pinion and/or the ring gear may be damaged. In the case where the rotation-restricted-engagement-type starter is used in the system, the member restricting the pinion rotation is forcibly rotated by the pinion which is unable to engage with the ring gear. As a result, the restricting member may be damaged.
In order to avoid the above problem, a locking device that prevents the inadvertent restart of the starter when the engine is running is provided in the key switch. The ignition key is prevented from being turned on to restart the starter by the locking device when rotation of the engine is detected. Alternatively, a starter relay is provided in the starter circuit for supplying current to the starter, and the starter relay is controlled to be kept open, even if the key switch is closed to restart the starter when the engine is running. The operation of the locking device and the starter relay may be controlled by an electronic control unit.
According to the present invention, possible damages of the pinion or the rotation-restricting member, which are caused by the inadvertent restart of the starter when the engine is running, are prevented by adding a simple device or structure in the starter system.
Other objects and features of the present invention will become more readily apparent from a better understanding of the preferred embodiments described below with reference to the following drawings.,